The present invention relates to a method of improving the wear resistance and other properties of a non-metallic, i.e. plastic, article by forming a metal-filled-resin composite surface thereon. More particularly the invention relates to forming a metal-filled-resin composite surface on a fiber-reinforced plastic composite shaped article by adhering thereto a "metal cloth" which is a formed fibrillated polymer containing entrapped metal or other particles in the fibrils.
Plastic composites have been known for several years. However this use has not been accepted in many applications due to unacceptably excessive wear, lack of electrical conductivity, poor environmental resistance in certain cases and other such problems. The art is replete with attempts at modifying such composites by incorporating metals or other materials therein to overcome these and other limitations. For example, U.S. Pat. No. 3,708,387 discloses metallic modified plastic compositions prepared by blending polymer particles with metal particles and then compacting the mixture in a cavity mold which results in an essentially uniform metal distribution throughout the polymer phase. U.S. Pat. No. 4,278,729 discloses the production of carbon fiber-tantalum carbide composites by vacuum infiltration of three-dimensional graphite yarn preforms by metal salt solutions. U.S. Pat. No. 3,211,584 discloses a radar antenna wherein a liquid epoxy resin is coated onto an antenna structure and then relatively coarse electrically conductive metallic power is dusted onto the liquid epoxy surface and adheres thereto. U.S. Pat. No. 3,726,737 discloses a method for producing multi-layer thin films of silicon carbide materials by taking cellulosic sheets, impregnating with a resinous material, carbonizing and then silicon-carbonizing the resultant structure. U.S. Pat. No. 2,689,380 discloses a method of making polytetrafluorethylene-containing bearings by applying the polymer in powder or sheet form onto the surface of a porous metallic structure produced by sintering metallic powder and then pressing the polymer into the metallic structure. U.S. Pat. No. 3,515,068 discloses embedding a woven wire fabric in a plastic explosive to strengthen and reinforce the explosive.
Metallic coatings have also been deposited upon metallic substrates to provide a hardface having improved wear and/or corrosion properties. Imperial Clevite, Inc., has commercialized a metallic coating under the trade name "Conforma Clad" which adheres the metal in the "metal cloth" utilized in the present invention to metallic substrates by overlaying the "metal cloth" with a brazing alloy and then heating to evaporate the polymer component of the "metal cloth" and to cause the brazing alloy to infiltrate the metal component of the "metal cloth" and thus bind it to the metallic substrate. The process of making the "metal cloth" is disclosed in U.S. Pat. Nos. 3,743,556; 3,778,586; 3,864,124 and 4,194,040 and a method of its use on metal substrates in U.S. Pat. No. 4,624,860. Articles which have been published on the use of "Conforma Clad" to coat metallic substrates include "Conforma Clad.TM.--A new Process for Customized Coatings" by Manek R. Dustoor in Refractory and Hard Metals, March, 1983, and "New Method of Applying Wear Resistant Coatings" by Dennis E. Shewell in Metal Progress, November 1983.
Accordingly, it is an object of the present invention to provide a means for applying a uniform metal-filled-resin coating on a shaped plastic article.
Another object of this invention is to provide a means for attaching a "metal cloth" to a non-metallic material which would be destroyed by the temperatures required to attach the same cloth to a metallic substrate.
Another object of this invention is to produce a shaped plastic composite article having solely a surface which is a metal-filled-resin composite.
Another object of this invention is to provide a method for modifying the surface properties of a shaped plastic article.
Another object of this invention is to provide a method for forming a shaped plastic composite article and modifying the surface properties thereof in a single molding operation.
These and other objects will become apparent to those skilled in the art from a reading of the following specification and claims.